Sort of? They said at one point that it wouldn't go longer than BB, which was five seasons (but the last was broken up into two, so that leaves sort of a grey area). LINK That article seems to think this could be the last season, though, so maybe it's not the best source... although, maybe it's right? I have no idea.
That's really, really brilliant. It could explain how morose he is after, too. (I mean, other than his overall existence.)
I'm going to say this isn't the last season based on AMC not hyping the hell out of it and stating that fact during every preview. I could certainly see them splitting up one longer final season over two years......as annoying as that is.